japanese home uses crafted timber sundial to support its passive system
japanese home uses crafted timber sundial to support its passive system japanese home uses crafted timber sundial to support its passive system
aug 20, 2015

japanese home uses crafted timber sundial to support its passive system

japanese home uses crafted timber sundial to support its passive system




this unusual home in japan by kikuma watanabe + d environmental design system laboratory has been designed to contain and use a sundial to operates its complete passive system. the internal spaces support a comfortable environment where in summer it is naturally cool and in the winter it is warm. this ecological technology aids this passive system using the sun and the wind for an effective air conditioner.



with this built-in sundial, the time can be told through shadow and the process of constructing this feature went through three steps:



1. designing the prototype of the sundial
at first we must plan the passive house as direct gain system. the window is based on the south side where the eaves shut off the intense sunlight in summer while receives it in winter. meanwhile insulation has been installed in the walls. for setting the sundial, the roof is inclined at the latitude of the site [34.60°]. under the roof we put the half cylinder inclined at the same angle and above the center of the cylinder, the top light is set where the time can be told through the position of the line

2. adapting to the site environment
the site has an irregular shape, and as a result of putting the sundial facing south, there are a diverse number of views to the gardens. the site has a gentle slope from west to east, and the floor level of kitchen, office, half area of living room is at -1000mm from ground level. the main opening has been oriented to the east where it faces onto the ponds, hills and historic scenery in the area.

3. planning by orientation
the plan of passive house sundial is divided into two areas. the brighter of the two contains the living and kitchen. meanwhile, the other is north facing area in where the atelier is and between the two, small spaces such as the bath and toilet are set along the east and west axis.


overall view from southeast




‘the sundial tells us not only time but also existence of cosmos.
adaptation to the site reminds us the gentle of the earth.
we live on the mother earth.
we live under the father sky
we live in the universe.
in this house we can feel that we live in the universe.
that is reason why we name this house “ home between earth and sky.’

the house is based on the top of small hill

view of the sundial from central axis. liner light tells us the time [11:30 am] (right)

rooms around the sundial: room of sunrise (left), room of sunset (right)

living room where is set in south bright area

the atelier space

looking up view of the sundial from atelier wooden beams are set every 7.5°(-half hour).

storage: room of cave (left), corridor of shadow where is under the sundial (right)

spacial diagram by model

1st floor plan+2nd floor plan

sectional composition+diagram of the passive system



project info:



location: kasugaoka, heguri, ikoma district, nara pref. japan
owner: kikuma watanabe
year of completion: 2015
architects: kikuma watanabe + d environmental design system laboratory
structural engineer: syunya takahashi+d environmental design system laboratory
construction: fushimi builder’s office
site area: 357.41m2
building area: 98.87m2
total floor area: 143.97m2
structure: conventional wood structure –yoshinosugi: japanese cedar cut in south mountain area in nara



designboom has received this project from our ‘DIY submissions’ feature, where we welcome our readers to submit their own work for publication. see more project submissions from our readers here.


  • Your severity of simplicity on the long wall of the exterior & the design of the air flow deserves applause. The sun dail is fun yet the interior might be popular but not my living tastes. I do not care to have the framing motif of the interior compete or upstage my furniture.

    lula says:

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